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Collection and cooking of wild vegetables have provided seasonal enjoyments for Japanese local people as provisioning and cultural ecosystem services. However, the Fukushima Daiichi Nuclear Power Plant accident in March 2011 caused extensive radiocesium contamination of wild vegetables. Restrictions on commercial shipments of wild vegetables have been in place for the last 10 years. Some species, including buds of Aralia elata, are currently showing radiocesium concentrations both above and below the Japanese reference level for food (100 Bq/kg), implying that there are factors decreasing and increasing the 137Cs concentration. Here, we evaluated easy-to-measure environmental variables (dose rate at the soil surface, organic soil layer thickness, slope steepness, and presence/absence of decontamination practices) and the 137Cs concentrations of 40 A. elata buds at 38 locations in Fukushima Prefecture to provide helpful information on avoiding collecting highly contaminated buds. The 137Cs concentrations in A. elata buds ranged from 1 to 6,280 Bq/kg fresh weight and increased significantly with increases in the dose rate at the soil surface (0.10–6.50 μSv/h). Meanwhile, the 137Cs concentration in A. elata buds were not reduced by decontamination practices. These findings suggest that measuring the latest dose rate at the soil surface at the base of A. elata plants is a helpful way to avoid collecting buds with higher 137Cs concentrations and aid in the management of species in polluted regions. [ABSTRACT FROM AUTHOR]

The aggregated transfer factor (Tag) is commonly used to represent the actual transfer of radiocesium from soil to wild edible plants, but the values have shown substantial variation since the Fukushima nuclear accident. To elucidate the factors causing this variation, we investigated the effects of spatial scale and vertical 137Cs distribution in the soil on the variation of Tag-137Cs values for one of the most severely contaminated wild edible plants, Eleutherococcus sciadophylloides Franch. et Sav. (Koshiabura). The variation in Tag-137Cs values was not reduced by direct measurement of 137Cs deposition in soil samples from the Koshiabura habitat, as a substitute for using spatially averaged airborne survey data at the administrative district scale. The 137Cs activity concentration in Koshiabura buds showed a significant positive correlation with the 137Cs inventories only in the organic horizon of soil from the Koshiabura habitat. The ratio of 137Cs inventories in the organic horizon to the total 137Cs deposition in soil exhibited substantial variation, especially in broad-leaved deciduous forests that Koshiabura primarily inhabits. This variation may be the cause of the wide range of Tag-137Cs values observed in Koshiabura buds when calculated from the total 137Cs deposition in soil. [ABSTRACT FROM AUTHOR]

Forest–stream ecotones possess prominent detritus-based food webs, and 137Cs-contaminated litter can influence the contamination levels of animals inhabiting such ecosystems. The effects of leaching on contaminated litter induce greater absolute differences between the 137Cs concentrations of forest and stream litter in more contaminated sites. Because 137Cs concentrations in litter can be attenuated temporally, spatiotemporal patterns in the differences in 137Cs concentrations between forest and stream litter may vary depending on both the amount of 137Cs deposition and the passage of time. To test this hypothesis, we sampled coniferous needle and broad-leaved deciduous litter in forests and streams at seven forested headwater sites affected by the Fukushima nuclear accident 3.24 and 11.24 years after the accident. We found that 137Cs concentrations in the two litter types were one order of magnitude lower 11.24 years after the accident than 3.24 years afterwards. The absolute difference in 137Cs activity concentrations of litter between forest and stream ecosystems was higher at more contaminated sites both 3.24 and 11.24 years after the accident. The spatiotemporal changes in litter contamination provide insight into 137Cs dynamics and complex transfer in the detritus-based food webs of forest–stream ecotones. [ABSTRACT FROM AUTHOR]

We proposed a mixture of animal husbandry and fruit tree industry: livestock grazing under an orchard layer to increase agricultural productivity per area and reduce the costs of feed, fertilizer, and weed control. Lambs were reared in‐house for 1 month and then moved to a pear orchard for 1 month of grazing. We recorded the changes in body weight, blood properties (e.g., albumin, cholinesterase, and nonesterified fatty acids), and parasitic infection to compare the in‐housed lambs with the grazing lambs in the orchard. Additionally, we conducted field investigations for changes in vegetation and soil properties before and after grazing. Grazing caused significant increases in body weight, helminth eggs in dung, and soil water retention, and significant decreases in plant biomass, grass digestibility, and soil hardness. In contrast, the nutritional values of the feed, blood properties, and soil chemical properties (e.g., pH, P, N, and C) were not significantly changed after grazing. These results highlighted that the fruit tree industry combined with livestock production would be an acceptable management approach for Japanese agriculture, although further case studies are required. [ABSTRACT FROM AUTHOR]

Understanding the factors influencing 137Cs concentrations in freshwater salmonids is crucial for reviving inland fisheries in polluted regions. We studied seasonal variations of 137Cs concentration in charr (Salvelinus leucomaenis) through uptake and metabolism in forested headwaters at Fukushima and Gunma sites. Charr consumed both terrestrial and aquatic animals, and terrestrial prey was predated more in summer at both sites. The 137Cs concentrations in litter, which is a dominant basal food resource of both forest and stream ecosystems, differed between forest and stream due to 137Cs leaching effect on litter submerged in streams. The concentration difference in both litter and prey was greater at Fukushima site than at Gunma site. The estimated prey 137Cs concentration at Fukushima site peaked in summer when terrestrial preys are most available, whereas it remained relatively constant at Gunma site because of the small difference of 137Cs concentrations in between terrestrial and aquatic preys. The specific metabolic rate of charr was commonly changed with stream water temperature, greatest in summer, and lowest in winter at both sites. Because both prey 137Cs concentrations and specific metabolic rates peaked in summer, the combination of uptake and metabolism at Fukushima site largely negated seasonal 137Cs fluctuations in charr, whereas specific metabolic rate fluctuations could be the major determinant of charr 137Cs concentrations at Gunma site. Our results suggested that 137Cs concentrations in prey items, whose seasonality are varied due to initial 137Cs fallout volume, were expected to be an important determinant for 137Cs concentrations in charr. [ABSTRACT FROM AUTHOR]

Forest-stream ecotones possess prominent detritus-based food webs, and 137 Cs-contaminated litter can influence the contamination levels of animals inhabiting such ecosystems. The effects of leaching on contaminated litter induce greater absolute differences between the 137 Cs concentrations of forest and stream litter in more contaminated sites. Because 137 Cs concentrations in litter can be attenuated temporally, spatiotemporal patterns in the differences in 137 Cs concentrations between forest and stream litter may vary depending on both the amount of 137 Cs deposition and the passage of time. To test this hypothesis, we sampled coniferous needle and broad-leaved deciduous litter in forests and streams at seven forested headwater sites affected by the Fukushima nuclear accident 3.24 and 11.24 years after the accident. We found that 137 Cs concentrations in the two litter types were one order of magnitude lower 11.24 years after the accident than 3.24 years afterwards. The absolute difference in 137 Cs activity concentrations of litter between forest and stream ecosystems was higher at more contaminated sites both 3.24 and 11.24 years after the accident. The spatiotemporal changes in litter contamination provide insight into 137 Cs dynamics and complex transfer in the detritus-based food webs of forest-stream ecotones.

Understanding the seasonality of 137 Cs concentrations in aquatic animals is crucial for reviving local inland fisheries. The seasonality of 137 Cs concentrations in animals is expected to vary, even if focal species consume similarly contaminated foods because the 137 Cs excretion rate is species-specific, and 137 Cs uptake by foraging autochthonous food resources also vary among seasons. Here, we conducted a seasonal monitoring survey of dissolved 137 Cs concentrations as an indicator of the contamination level of food resources and measured 137 Cs concentrations in two carnivorous aquatic animals (Palaemon paucidens and Rhinogobius sp.) that share a trophic niche in a stream connected to a dam reservoir. The dissolved 137 Cs concentration had clear seasonality-high in summer and low in winter. The 137 Cs concentrations in the animals revealed a different seasonal pattern-it peaked in October in P. paucidens and peaked in February in Rhinogobius. Overall, the 137 Cs concentration was relatively higher in P. paucidens than in Rhinogobius, suggesting that P. paucidens has a lower excretion rate than Rhinogobius. Consequently, the seasonality of the 137 Cs concentration in P. paucidens showed temporal changes similar to those of the dissolved 137 Cs concentration, which were likely affected by 137 Cs uptake through foraging, whereas that in Rhinogobius was controlled by 137 Cs excretion. This study shows that the seasonality of 137 Cs concentration can differ between sympatric animals that share a trophic niche. Accumulating knowledge and comparing the seasonality of 137 Cs concentrations in fisheries species based on the balance between uptake and excretion will be valuable to determine the appropriate seasons to obtain less-contaminated products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)